Though unapologetically partial to his subject, an idealistic computer genius who committed suicide in 2013 at 26, Mr. Knappenberger keeps his images simple and allows his facts to take precedence. Clips of Mr. Swartz in home movies and at speaking engagements chart his growth from child prodigy to Internet crusader who believed that the contents of public-interest databases should be freely available to all. Detailed in his Guerrilla Open Access Manifesto, this ethos would lead to his 2011 arrest based on charges that he downloaded millions of journal articles from a subscription-only online service — or, in the words of the writer Cory Doctorow, “for taking too many books out of the library.”

Making room for the moral and philosophical underpinnings of freedom of information, and questioning the motives of its opponents, the film’s many contributors — including family, friends and experts like Tim Berners-Lee, the inventor of the World Wide Web — generate a “how could this happen?” tone that feels agonizingly appropriate. None more so than the writer Quinn Norton, who’s commendably candid about (and clearly still haunted by) her cooperation with federal prosecutors. Their pursuit of Swartz placed them, she believes, “on the wrong side of history.” Few who watch this film will feel inclined to disagree.